Semiconductor device

ABSTRACT

A semiconductor device which is designed based on RDR, suppresses the occurrence of a trouble at the boundary between an active region and a power wire and therearound and is small in size and highly integrated. The semiconductor device includes a first conductive impurity region for functional elements which is formed over the main surface of a semiconductor substrate and a second conductive impurity region for power potential to which power potential is applied in at least one standard cell. It also includes insulating layers which are formed over the main surface of the semiconductor substrate and have throughholes reaching the main surface of the semiconductor substrate, and a conductive layer for contact formed in the throughholes of the insulating layers. The impurity region for functional elements and the impurity region for power potential are electrically coupled to each other through the conductive layer for contact which is formed astride the impurity region for functional elements and the impurity region for power potential.

CROSS-REFERENCE TO RELATED APPLICATIONS

The disclosure of Japanese Patent Application No. 2010-110296 filed onMay 12, 2010 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND

The present invention relates to a semiconductor device and,specifically, to a semiconductor device having a plurality of standardcells.

As the performance of a semiconductor device is becoming higher andhigher, efforts are being made to reduce the size and increase theintegration of the semiconductor device. To obtain a small-sized highlyintegrated semiconductor device, layout design for achieving a smallercell width and a smaller cell height is becoming the mainstream in thisfield. In the case of SRAM (Static Random Access Memory) which is a typeof volatile memory, like an integrated circuit disclosed by JapaneseUnexamined Patent Publication No. 2009-130238 (Patent Document 1),linear load transistors and active regions are inclined at a certainangle with respect to the extension direction of standard cells in aplan view. This structure provides high integration as compared to anintegrated circuit in which all of the above load transistors and activeregions are not inclined in the extension direction of the standardcells, thereby reducing the size of the standard cells.

SUMMARY

In the design of a semiconductor device, particularly after the 45 nmgeneration, a design technique called “RDR (Restrictive Design Rule)”has been employed or studied. Stated more specifically, RDR is a verystrict design rule and employs one-dimensional layout which prohibitsbending and curving in place of two-dimensional layout in which a metalwire and a polycrystalline silicon wire is bent or curved. Thereby,variations caused by the dependence on shape of transistors and wiresare suppressed, and EDA (Electronics Design Automation) burdens such asDRC (Design Rule Check), OPC (Optical Proximity Correction) andlithography check are reduced. That is, the occurrence of variations inlithography and the complication of design can be suppressed by RDR. Inother words, according to RDR, like SRAM of Japanese Unexamined PatentPublication No. 2009-130238, load transistors and active regions arepreferably not bent in the plan view.

Meanwhile, as a process technique for the reduction of size and theincrease of integration, so-called “butting diffusion structure” inwhich the active regions (such as source/drain regions) of maintransistors and active regions to which a power potential is applied aredirectly coupled to each other is often used. When this buttingdiffusion structure is used, as compared to a case in which they arecoupled to each other by means of contact electrodes and metal wires asshown in Japanese Laid-open Patent Application No. 2009-130238, it iseasy to arrange gate electrodes at a narrower pitch than the pitch ofthe contact electrodes.

However, when the butting diffusion structure is used, an areasurrounded by the active regions and the power wires in three directionsin the plan view is formed. In this area surrounded by the activeregions in three directions, it is made difficult to bury an STI(Shallow Trench Isolation) insulating film by the rounding of the activeregions, and the active regions are apt to vary in planar shape.

In the butting diffusion structure, p type source/drain regions formedin an n type well are coupled to an n⁺ impurity region for applying apower potential to the n type well with the result that a pn junction isformed between them. Therefore, according to the condition of applyingvoltage to the power wires, a depletion layer is formed at the boundarybetween the p type source/drain regions and the n⁺ impurity region withthe result that the butting diffusion structure may cause disconnection.That is, a problem may occur in the wiring of the butting diffusionstructure.

It is an object of the present invention which has been made in view ofthe above problem to provide a semiconductor device which is designedbased on RDR, suppresses the occurrence of a trouble at the boundarybetween the active region and the power wire and therearound and issmall in size and highly integrated.

A semiconductor having a plurality of standard cells according to anembodiment of the present invention has the following structure.

The above semiconductor device includes a semiconductor substrate havinga main surface. The above semiconductor device includes a firstconductive impurity region for functional elements which is formed overthe main surface of the semiconductor substrate in at least one of thestandard cells and forms functional elements and a second conductiveimpurity region for power potential which is formed over the mainsurface of the semiconductor substrate in at least one of the standardcells and to which power potential is applied. The above semiconductordevice includes insulating films which are formed over the main surfaceof the semiconductor substrate and have throughholes reaching the mainsurface of the semiconductor substrate and a conductive layer forcontact which is formed in the throughholes of the insulating layers.Since the conductive layer for contact is formed astride the aboveimpurity region for functional elements and the impurity region forpower potential, the impurity region for functional elements and theimpurity region for power potential are electrically coupled to eachother through the conductive layer for contact.

A semiconductor device having a plurality of standard cells according toanother embodiment of the present invention has the following structure.

The above semiconductor device includes a semiconductor substrate havinga main surface. The above semiconductor device has a pair ofsource/drain regions for transistors which are spaced apart from eachother over the main surface of the semiconductor substrate. The abovesemiconductor device has a transistor gate electrode formed over themain surface of the semiconductor substrate and sandwiched between thepair of source/drain regions, and first and second power wires which areformed above the gate electrode over the main surface of thesemiconductor substrate and separate from each other in at least one ofthe standard cells, and a conductive layer for coupling which isseparate from the same layer as the gate electrode. The above conductivelayer for coupling is separate from the same layer as the gate electrodeand made of the same material as the gate electrode. The first andsecond power wires and the conductive layer for coupling extend in thesame direction. In the plan view, part of the first power wire and partof the conductive layer for coupling are overlapped with each other, andpart of the second power wire and part of the conductive layer forcoupling are overlapped with each other. The first and second powerwires are electrically coupled to each other through the conductivelayer for coupling.

In the semiconductor device according to the embodiment of the presentinvention, the impurity region for functional elements and the impurityregion for power potential are electrically coupled to each otherthrough the conductive layer for contact. Therefore, even whendisconnection occurs at the boundary between the impurity region forfunctional elements and the impurity region for power potential,conduction between the impurity region for functional elements and theimpurity region for power potential can be secured through theconductive layer for contact.

In the semiconductor device according to the other embodiment of thepresent invention, the power wire is divided into first and second powerwires. Therefore, the area surrounded by the power wires and the activeregions in three directions in the plan view becomes small. Therefore,it is easy to bury the insulating layer near the power wires and theactive regions, thereby suppressing variations in the shapes of thepower wires and the active regions.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic plan view showing the configuration of asemiconductor device according to First Embodiment of the presentinvention;

FIG. 2 is a circuit diagram showing the circuit configuration offunctional elements formed in one of a plurality of standard cells shownin FIG. 1;

FIG. 3 is a schematic diagram showing the arrangement of the standardcells of the semiconductor device according to First Embodiment of thepresent invention;

FIG. 4 is a schematic plan view showing the configurations of the firstlayer of the standard cells and the semiconductor substrate of thesemiconductor device of First Embodiment of the present invention;

FIG. 5 is a schematic plan view showing the configuration of the secondlayer of the standard cells shown in FIG. 4;

FIG. 6 is a schematic plan view showing the configuration of the thirdlayer of the standard cells shown in FIG. 4;

FIG. 7 is a schematic partial sectional view cut on line VII-VII inFIGS. 4 to 6 of the semiconductor device according to First Embodimentof the present invention;

FIG. 8 is a schematic partial plan view showing an example of a contactportion formed in the semiconductor device according to First Embodimentof the present invention;

FIG. 9 is a schematic partial plan view showing an example differentfrom that of FIG. 8 of a contact portion formed in the semiconductordevice according to First Embodiment of the present invention;

FIG. 10 is a schematic partial plan view showing an example differentfrom that of FIG. 9 of a contact portion formed in the semiconductordevice according to First Embodiment of the present invention;

FIG. 11 is a detailed perspective view showing the configuration of anarea in which an n type impurity region and a p type impurity region arecoupled to each other in the semiconductor device according to FirstEmbodiment of the present invention;

FIG. 12 is a perspective view as a comparative example of FIG. 11;

FIG. 13 is a schematic partial sectional view of a semiconductor deviceaccording to Second Embodiment of the present invention;

FIG. 14 is a detailed sectional view showing the configuration of anarea in which an n type impurity region and a p type impurity region arecoupled to each other in the semiconductor device according to SecondEmbodiment of the present invention;

FIG. 15 is a detailed perspective view showing the configuration of anarea in which an n type impurity region and a p type impurity region arecoupled to each other in a semiconductor device according to ThirdEmbodiment of the present invention;

FIG. 16 is a detailed perspective view showing an example different fromthat of FIG. 15 of the area in which the n type impurity region and thep type impurity region are coupled to each other in the semiconductordevice according to Third Embodiment of the present invention;

FIG. 17 is a schematic plan view showing the configurations of the firstlayer of a plurality of standard cells and the semiconductor substrateof a semiconductor device according to Fourth Embodiment of the presentinvention;

FIG. 18 is a schematic plan view showing the configuration of the secondlayer of the standard cells shown in FIG. 17;

FIG. 19 is a schematic plan view showing the configuration of the thirdlayer of the standard cells shown in FIG. 17;

FIG. 20 is a detailed perspective view showing an example of an area inwhich an n type impurity region and a p type impurity region are coupledto each other in the semiconductor device according to Fourth Embodimentof the present invention;

FIG. 21 is a detailed perspective view showing an example different fromthat of FIG. 20 of the area in which the n type impurity region and thep type impurity region are coupled to each other in the semiconductordevice according to Fourth Embodiment of the present invention;

FIG. 22 is a detailed perspective view showing an example of an area inwhich an n type impurity region and a p type impurity region are coupledto each other in a semiconductor device according to Fifth Embodiment ofthe present invention;

FIG. 23 is a schematic partial plan view showing the configuration ofFIG. 22;

FIG. 24 is a schematic partial plan view showing the configuration of alower layer shown in FIG. 22;

FIG. 25 is a schematic plan view showing that an active region and animpurity region for power potential made of different materials arecoupled to each other;

FIG. 26 is a schematic plan view showing that the active region and theimpurity region for power potential made of the same material arecoupled to each other;

FIG. 27 is a partial plan view as a comparative example of FIG. 23; and

FIG. 28 is a partial plan view as a comparative example of FIG. 24.

DETAILED DESCRIPTION

Preferred embodiments of the present invention will be describedhereinunder with reference to the accompanying drawings.

First Embodiment

With reference to FIG. 1, a semiconductor device SDV (for example, asemiconductor chip) has a standard cell region CELR, I/O (Input/Output)cell regions I/O arranged around the standard cell region CELR and a pad(not shown) used for input/output from the outside as the maincomponents on the surface.

The standard cell region CELR has a plurality of standard cells CELwhich are arranged in an X direction and a Y direction orthogonal tothis X direction in a matrix form in the figure. Each of the standardcells CEL is surrounded by outer rims which extend in the X directionand are opposed to each other and outer rims which extend in the Ydirection and are opposed to each other. The standard cell is a basiclogic cell arranged by an automatic arrangement technique to achieve adesired function in the semiconductor device. In SOC (System On Chip)using a standard cell library, a CPU (Central Processing Unit), RAM(Random Access Memory), FIFO (First-In First-Out), SCSI (Small ComputerSystem Interface) and SOG (Sea Of Gate) are formed in this standard cellregion CELR.

With reference to FIG. 2, the circuit of a functional element to beformed in this standard cell CEL is, for example, a flip-flop. Thisflip-flop has a data input terminal DT, an output terminal QB, a clockterminal CK, power terminals VDD and VSS, pMIS (Metal InsulatorSemiconductor) transistors PT and nMIS transistors NT. In this figure, aplurality of wires TC are electrically coupled to one another. Also, aplurality of wires TT are electrically coupled to one another.

With reference to FIG. 3, the semiconductor device of this embodimenthas standard cells Civ, Cnd, Cnr and Cfl. The standard cells Civ, Cnd,Cnr and Cfl are arranged in a plurality of tiers in the X direction inthe figure.

The standard cells Civ, Cnd and Cnr are for achieving invertor, 2NANDand 2NOR functions, respectively. 2NAND is a NAND having two inputsystems and 2NOR is a NOR having two input systems. The standard cellCfl is a filler cell (gap cell).

With reference to FIGS. 4 to 6, the standard cells Civ, Cnd, Cnr and Cflare arranged in the same manner as in FIG. 3 in these figures and theplanar areas of the standard cells Civ, Cnd, Cnr and Cfl are partitionedby one-dotted chain lines. As described above, FIG. 7 is a schematicsectional view cut on line VII-VII of FIGS. 4 to 6.

FIG. 4 is a plan view showing a relatively lower layer in FIG. 7, thatis, a semiconductor substrate SB, n type active regions An and p typeactive regions Ap (impurity regions for functional elements), contactportions CT and contact portions SCT which are formed over the mainsurface of the semiconductor substrate SB, and gate wires GW (gateelectrodes) not shown in FIG. 7. The main surface means a surface havinga largest area out of the surfaces of the semiconductor substrate SB.

FIG. 5 is a plan view showing an intermediate layer in FIG. 7, that is,first metal wires M1 and contact portions CT and SCT. The first metalwires M1 include transistor coupling wires and power wires (VDD wires,VSS wires) VDD and VSS. Further, FIG. 6 is a plan view showing arelative upper layer in FIG. 7, that is, second metal wires M2 and viasV1. In the plan views of FIG. 5 and FIG. 6, the contact portions CT andthe first metal wires M1 arranged right below are shown by dotted lines.

With reference to FIG. 4 and FIG. 7, in the standard cells Civ, Cnd, Cnrand Cfl, n type well regions Wn and p type well regions Wp are formed inthe semiconductor substrate SB. The n type well regions Wn and the ptype well regions Wp extend like a band in the X direction of FIG. 4over the main surface of the semiconductor substrate SB, and the n typewell regions Wn and the p type well regions Wp region are arrangedalternately in the Y direction of FIG. 4. Thereby, the planar area ofeach standard cell is divided into the n type well region Wn and the ptype well region Wp in the Y direction. Adjacent standard cells in the Ydirection share either one of the n type well region Wn and the p typewell region Wp.

In FIG. 4, an STI region RE in which a separation insulation film isburied is formed in a trench devoice of the n type well region Wn andthe p type well region Wp. As shown in FIG. 7, the trench of this STIregion RE is deeper than the n type active region An and the p typeactive region Ap and shallower than the n type well region Wn and the ptype well region Wp.

A plurality of pMIS transistors as functional elements and an n typeimpurity region An for power potential are formed over the main surfaceof the semiconductor substrate SB in the n type well region Wn. Each ofthe pMIS transistors has a pair of p type source/drain regions Ap, agate insulating layer (not shown) and a gate wire GW. The pair of p typesource/drain regions Ap are spaced apart from each other over the mainsurface of the semiconductor substrate SB. The gate wire GW is formedover an area sandwiched between the pair of p type source/drain regionsAp through the gate insulating layer.

The gate wires GW extend linearly in the Y direction at equal intervals.The n type impurity region An for power potential is formed over themain surface of the semiconductor substrate SB in such a manner that itextends in the X direction along one (outer rim OTn) of the opposedsides in the Y direction of each standard cell. The n type impurityregion An for power potential extending in the X direction extendscontinuously in the standard cells arranged in the X direction and isshared by adjacent standard cells in the Y direction.

Similarly, a plurality of nMIS transistors as functional elements and ap type impurity region Ap for power potential are formed over the mainsurface of the semiconductor substrate SB in the p type well region Wp.Each of the nMIS transistors has a pair of n type source/drain regionsAn, a gate insulating layer (not shown) and a gate wire GW. The gatewire GW is formed over an area sandwiched between the pair of n typesource/drain regions An through the gate insulating layer.

The gate wires GW extend linearly in the Y direction at equal intervals.The p type impurity region Ap for power potential is formed over themain surface of the semiconductor substrate SB in such a manner that itextends in the X direction along one side (outer rim OTp) of the opposedsides in the Y direction of each standard cell. The p type impurityregion Ap for power potential extending in the X direction extendscontinuously in the standard cells arranged in the X direction and isshared by adjacent standard cells in the Y direction.

The first outer rim OTn and the second rim OTp described above arecenter lines in the plan view of the impurity regions An and Ap forpower potential which extend linearly, respectively.

The gate wires GW may be made of polycrystalline silicon or a metalmaterial containing at least one of titanium and copper. The gateinsulating layer may be composed of a silicon oxide film or made of aHigh-k dielectric material.

An insulating layer II1 is formed over the main surface of thesemiconductor substrate SB to cover the MIS transistors and the impurityregions An and Ap for power potential. This insulating layer II1 is, forexample, a silicon oxide film formed, for example, by a CVD (ChemicalVapor Deposition) method. A plurality of contact holes (throughholes)CTH and SCTH reaching the main surface of the semiconductor substrate SBare formed in this insulating layer II1. The contact holes CTH includecontact holes CTH reaching the surfaces of the source/drain regions Anand Ap and contact holes CTH reaching the surfaces of the gate wires GW.The contact holes SCTH include contact holes SCTH reaching both thesurface of the n type impurity region An for power potential and the ptype source/drain regions Ap and contact holes SCTH reaching both thesurfaces of the p type impurity region Ap for power potential and the ntype source/drain regions An.

The contact holes CTH and SCTH are filled with a contact layer PCL(conductive layer for contact) made of a metal. The contact layer PCL inthe contact holes CTH is in contact with the source/drain regions An andAP or the gate wire GW to form a contact portion CT. The contact layerPCL in the contact holes SCTH reaching both the surfaces of the n typeimpurity region An for power potential and the p type source/drainregions Ap is in contact with both the n type impurity region An forpower potential and the p type source/drain regions Ap to form a contactportion SCT. Thereby, the n type impurity region Ap and the p typesource/drain regions Ap are electrically coupled to each other throughthe contact layer PCL. The contact layer PCL in the contact holes SCTHreaching the surfaces of the p type impurity region Ap for powerpotential and the n type source/drain regions An is in contact with thep type impurity region Ap for power potential and the n typesource/drain regions An to form a contact portion SCT. Thereby, the ptype impurity region Ap for power potential and the n type source/drainregions An are electrically coupled to each other through the contactlayer PCL.

In this embodiment, the n type impurity region An for power potentialand the p type source/drain regions Ap are directly coupled to eachother and the p type impurity region Ap for power potential and the ntype source/drain regions An are directly coupled to each other rightbelow the contact portions SCT.

Preferably, the n type source/drain regions An described above are madeof SiC and the p type source/drain regions Ap are made of SiGe. By usingthese materials, current drive capability in these active regions isimproved.

The n type impurity region An for power potential and the p typeimpurity region Ap for power potential are preferably made of, forexample, Si. The functions of these impurity regions for power potentialextending linearly are stabilized by this.

With reference to FIG. 5 and FIG. 7, a plurality of first metal wires M1are formed over the insulating layer II1. The first metal wires M1extend in a direction (X direction) crossing the gate wires GW in theplan view. The first metal wires M1 include first wires M1 for powerpotential and first wires M1 for coupling. The first wires M1 for powerpotential include VDD wires M1 to which VDD potential is applied and VSSwires M1 to which VSS potential is applied.

The VDD wires M1 extend right above the n type impurity regions An forpower potential in the plan view, whereby they extend in the X directionalong the outer rim OTn. The VDD wires M1 extend continuously in thestandard cells arranged in the X direction and are shared by adjacentstandard cells in the Y direction. The VDD wires M1 are electricallycoupled to both the n type impurity regions An for power potential andthe p type source/drain regions Ap through the contact holes CTH andSCTH.

The VSS wires M1 extend right above the p type impurity regions Ap forpower potential in the plan view, whereby they extend in the X directionalong the outer rim OTp. The VSS wires M1 extend continuously in thestandard cells arranged in the X direction and are shared by adjacentstandard cells in the Y direction. The VSS wires M1 are electricallycoupled to the p type impurity regions Ap for power potential and the ntype source/drain regions An through the contact holes CTH and SCTH.

Each of the first wires M1 for coupling is electrically coupled to thesource/drain regions An and Ap or the gate wire GW through the contacthole CTH.

With reference to FIG. 6 and FIG. 7, an insulating layer II2 is formedover the insulating layer II1 to cover the first metal wires M1. Aplurality of via holes V1 reaching the first metal wires M1 are formedin this insulating layer II2. Each of the via holes V1 is filled with aconductive layer.

A plurality of second metal wires M2 are formed over the insulatinglayer II2. The second metal wires M2 extend in the same direction (Ydirection) as the gate wires GW in the plan view. The second metal wiresM2 are electrically coupled to the first metal wires M1 through the viaholes V1.

Preferably, the contact portions CT and the contact portions SCT do noproject from an area where the impurity region for power potential andthe impurity region for functional elements are formed and are situatedwithin the area in the plan view. More specifically, for example, asshown in FIG. 8, the contact portion SCT in contact with a junctionportion BD between the n type active region An and the p type impurityregion Ap for power potential is preferably situated within the n typeactive region An and the p type impurity region Ap for power potential.That is, the contact hole SCTH for forming the contact portion SCT ispreferably formed within the n type active region An and the p typeimpurity region Ap for power potential in the plan view.

In this case, the width W1 in the transverse direction in FIG. 8 of thecontact portion SCT is preferably smaller than the width W2 of the ntype region An or the p type region Ap near the junction portion BD.When the width W1 is made smaller than the width W2 and the contactportion SCT is situated within the active regions, if a contact shiftoccurs, it is possible to suppress the chipping of the STI region RE atthe time of forming the contact hole SCTH. Therefore, it is possible tosuppress a leak current from flowing between the contact portion SCT andthe well region of the active regions.

As a modification, for example, as shown in FIG. 9, the width W1 in thetransverse direction in FIG. 9 of the contact portion SCT may be largerthan the width W2 of the n type region An or the p type region Ap nearthe junction portion BD. In FIG. 9, the width L1 in the longitudinaldirection in FIG. 9 of the contact portion SCT is smaller than the totalwidth L2 of the n type region An and the p type region Ap near thejunction portion BD. However, as shown in FIG. 10, for example, thewidth W1 in the transverse direction in FIG. 9 of the contact portionSCT may be larger than the width W2 of the n type region An or the ptype region Ap near the junction portion BD and the width L1 in thelongitudinal direction in FIG. 10 may be larger than the total width L2of the n type region An and the p type region Ap near the junctionportion BD.

When the semiconductor elements are becoming finer and faster, it isdifficult to form fine contact holes SCTH and to form small contactholes SCTH over the active regions An and Ap in such a manner that theydo not overlap with the STI region RE in the plan view. Therefore, thecontact portions SCT as shown in FIG. 9 and FIG. 10 projecting from theactive regions An and Ap are formed. However, when the contact portionSCT overlapping with the STI region RE is formed, the STI region RE ischipped at the time of forming the contact hole SCTH and a junction leak(a leak current at the junction portion) occurs between the well regionand the contact portion SCT.

Then, when contact portions SCT as shown in FIG. 9 and FIG. 10 are to beformed, at least active regions (impurity regions An and Ap for powerpotential, n type source/drain regions An and p type source/drainregions Ap) near the contact portions SCT are preferably higher than theSi surface which is the main surface of the semiconductor substrate SBon which functional element are to be formed. To this end, it ispreferred that the impurity region An for power potential and the n typesource/drain regions An should be made of SiC and the impurity region Apfor power potential and the p type source/drain regions Ap should bemade of SiGe.

Then, the depth of the contact hole SCTH can be made small, and evenwhen it overlaps with the STI region RE, the chipping of the STI regionRE can be suppressed at the time of forming the contact hole SCTH.Therefore, the occurrence of the above junction leak can be suppressed.

FIG. 11 is a schematic perspective view of a portion where the n typeregion An (n type impurity region for power potential) and the p typeregion Ap (p type impurity region for functional elements as an activeregion such as source/drain regions) in the n type well region Wn out ofthe circuits shown in FIGS. 4 to 7 are coupled to each other. Withreference to FIG. 11 and FIGS. 4 and 5, the linear n type impurityregion An for power potential and the p type impurity region Ap forfunctional elements are joined together at the junction portion BD.

In FIG. 11, a contact layer PCL for electrically coupling the aboveimpurity region An for power potential and the impurity region Ap forfunctional elements to each other is formed. The lowermost part of thiscontact layer PCL is a contact portion SCT which is in contact with boththe impurity region An for power potential and the impurity region Apfor functional elements.

The uppermost part of the contact layer PCL having this contact portionSCT is coupled to a power wire M1 to which VDD is applied. This powerwire M1 is electrically coupled to the impurity region An for powerpotential by the contact layer PCL having the contact portion CT whichis the lowermost part. A power wire M1 to which VSS is applied is alsoelectrically coupled to the impurity region Ap for power potential andthe impurity region An for functional elements like the power wire towhich VDD is applied.

In FIG. 11, the insulating layers II1 and II2, the semiconductorsubstrate SB, the via holes V1 and the wires M2 are not shown.

A description is subsequently given of the function and effect of thesemiconductor device SDV of this embodiment with reference mainly toFIG. 11 and FIG. 12.

In the semiconductor device SDV of this embodiment, for example, asshown in FIG. 11, the impurity region Ap for functional elements and theimpurity region An for power potential are coupled to each other at thejunction portion BD. FIG. 12 for comparison is different from FIG. 11only in that the contact layer PCL having the contact portion SCT is notformed.

For instance, when the contact layer PCL having the contact portion SCTwhich is in contact with both the impurity region Ap for functionalelements and the impurity region An for power potential is not formed asshown in FIG. 12 and the potential of a power terminal VDD is applied tothe impurity region An for power potential, a depletion layer may beformed near the junction portion BD. This is because the p type impurityregion Ap for functional elements and the n type impurity region An forpower potential are joined together at the junction portion BD to form apn junction.

When the depletion layer is formed, disconnection between the impurityregion Ap for functional elements and the impurity region An for powerpotential may occur at the junction portion BD. Then, as shown in FIG.11, the contact layer PCL having the contact portion SCT forelectrically coupling the impurity region Ap for functional elements andthe impurity region An for power potential is formed. Thereby, even whena large depletion layer is formed between the impurity region Ap forfunctional elements and the impurity region An for power potential,conduction between the impurity region Ap for functional elements andthe impurity region An for power potential is secured by the contactlayer PCL. Consequently, the semiconductor device SDV can be made smallin size and highly integrated without any problem while theone-dimensional layout of the gate wires GW, the first metal wires M1and the second metal wires M2 is maintained.

Further, for example, when the power wire (first metal wire) M1 isformed in contact with the uppermost part of the contact layer PCLhaving the contact portion SCT as shown in FIG. 11, if a large depletionlayer is formed at the junction portion BD, electrical coupling betweenthe impurity region An for power potential and the impurity region Apfor functional elements can be secured by coupling between the powerwire M1 and the contact layer PCL having the contact portion SCT (forexample, when the power wire M1 is electrically coupled to both theimpurity region An for power potential and the impurity region Ap forfunctional elements). Therefore, electrical coupling between theimpurity region An for power potential and the impurity region Ap forfunctional elements can be made more certain.

Particularly when the n type source/drain regions An are made of SiC,the p type source/drain regions Ap are made of SiGe, and the n typeimpurity region An for power potential and the p type impurity region Apfor power potential are made of Si, the junction portion BD becomes theboundary between SiC and Si and the boundary between SiGe and Si. SinceSiC and Si are different from each other in crystal structure,electrical insulation readily occurs at the junction portion BD wherethey are joined together. This is because it is difficult to form alow-resistance silicide layer for smoothing conduction between SiC andSi. The same can be said of SiGe and Si.

Therefore, it is particularly effective that electrical coupling betweenthe impurity region An for power potential and the impurity region Apfor functional elements should be ensured by forming the contact layerPCL as shown in FIG. 11.

Second Embodiment

This embodiment differs from First Embodiment in the structures of theimpurity regions coupled by the contact layer PCL. A description issubsequently given of the configuration of this embodiment.

FIG. 13 is a sectional view of the same part as in FIG. 7 of thestandard cell of this embodiment. FIG. 14 is a perspective view of thesame part as in FIG. 11 of the standard cell of this embodiment.

With reference to FIG. 13 and FIG. 14, FIG. 13 differs from FIG. 7 inthat the p type active region Ap and the impurity region An for powerpotential are not joined together right below the contact portion SCT(contact region) and separate from each other. The difference betweenFIG. 14 and FIG. 11 is the same as the difference between FIG. 13 andFIG. 7. Although not shown, the same can be said of the n type activeregion An and the impurity region Ap for power potential to be formed inthe p type well region Wp, and the n type active region An and theimpurity region Ap for power potential are not joined together andseparate from each other.

That is, in this embodiment, the junction portion BD is not formedbetween the impurity region for functional elements and the impurityregion for power potential. However, even in this embodiment, as shownin FIG. 13 and FIG. 14, the contact portion SCT is in contact with boththe p type active region Ap and the impurity region An for powerpotential which are separate from each other. That is, the p type activeregion Ap and the impurity region An for power potential areelectrically coupled to each other by the contact layer PCL having thecontact portion SCT.

Also in this case, to eliminate a problem such as the occurrence of theabove junction leak, at least active regions (the impurity regions Anand Ap for power potential, the n type source/drain regions An and the ptype source/drain regions Ap) near the contact portion SCT arepreferably higher than the Si surface which is the main surface of thesemiconductor substrate SB on which functional elements are to beformed. To this end, it is preferred that the impurity region An forpower potential and the n type source/drain regions An should be made ofSiC and the impurity region Ap for power potential and the p typesource/drain regions Ap should be made of SiGe.

Since the configuration of this embodiment is almost the same as theconfiguration of First Embodiment except for the above point, the sameelements as in First Embodiment in FIG. 13 and FIG. 14 are given thesame reference symbols, and their descriptions are not repeated.

Thus, the impurity region for functional elements and the impurityregion for power potential which are electrically coupled to each otherby the contact layer PCL having the contact portion SCT may not bejoined together. Also in this case, conduction between the impurityregion for functional elements and the impurity region for powerpotential is maintained by the contact layer PCL and the power wire M1which is arranged in contact with and right above the contact layer PCL.

Second Embodiment of the present invention differs from First Embodimentof the present invention only in the above point. That is,configurations, conditions, procedures and effect which are notdescribed for Second Embodiment of the present invention are the same asin First Embodiment.

Third Embodiment

This embodiment differs from First Embodiment only in the configurationsof the contact layer PCL and the power terminal VDD. A description issubsequently given of the configuration of this embodiment.

FIG. 15 and FIG. 16 are perspective views of the same part shown as inFIG. 11 of the standard cell of this embodiment.

With reference to FIG. 15, FIG. 15 differs from FIG. 11 in that thepower wire M1 to which VDD is applied is not joined to the uppermostpart of the contact layer PCL having the contact portion SCT. That is,the power wire M1 and the contact layer PCL having the contact portionSCT are separate from each other in the plan view.

Since the power wire M1 and the contact layer PCL are not joinedtogether, the power wire M1 extends only in the direction of theimpurity region for power potential and the branched part as shown inFIG. 11 (for coupling the contact layer PCL having the contact portionSCT) does not exist.

However, FIG. 15 is the same as FIG. 11 of First Embodiment except forthe above points. That is, the impurity region Ap for functionalelements and the impurity region An for power potential are coupled toeach other at the junction portion BD. A contact layer PCL forelectrically coupling the impurity region An for power potential and theimpurity region Ap for functional elements is formed. That is, thelowermost part of the contact layer PCL is a contact portion SCT whichis in contact with both the impurity region An for power potential andthe impurity region Ap for functional elements.

Therefore, the impurity region Ap for functional elements and theimpurity region An for power potential are electrically coupled to eachother not by the power wire M1 but by the contact portion SCT.Consequently, like First Embodiment and Second Embodiment, conductionbetween the impurity region for functional elements and the impurityregion for power potential is maintained.

As another example, the configuration shown in FIG. 16 differs from theconfiguration of FIG. 11 in that the impurity region Ap for functionalelements and the impurity region An for power potential are not joinedtogether and separate from each other over the main surface of thesemiconductor substrate SB. The configuration shown in FIG. 16 alsodiffers from the configuration of FIG. 11 in that the contact portionSCT is in contact with the p type active region Ap but not with theimpurity region An for power potential. That is, in the contact portionSCT of FIG. 16, the p type active region Ap and the impurity region Anfor power potential are not electrically coupled to each other.

FIG. 16 differs from FIG. 11 in the above points. That is, in thestructure of FIG. 16, only the power wire M1 is electrically coupled tothe contact layer PCL having the contact portion SCT. Even in thisconfiguration, as long as the power wire M1 and the contact layer PCLare coupled to each other, conduction between the n type region An andthe p type region Ap is secured.

Third Embodiment of the present invention differs from First Embodimentof the present invention only in the above points. That is,configurations, conditions, procedures and effect which are notdescribed for Third Embodiment of the present invention are the same asin First Embodiment of the present invention.

Fourth Embodiment

This embodiment differs from First Embodiment in the configuration ofthe contact layer PCL for coupling the impurity regions. A descriptionis subsequently given of the configuration of this embodiment.

FIG. 17 is a similar plan view to the plan view FIG. 4 of the standardcell of this embodiment. FIG. 18 is a similar plan view to the plan viewof FIG. 5 of the standard cell of this embodiment. FIG. 19 is a similarplan view to the plan view of FIG. 6 of the standard cell of thisembodiment. Further, FIG. 20 is a similar perspective view to theperspective view of FIG. 11 of the standard cell of this embodimentshown in FIGS. 17 to 19.

With reference to FIGS. 17 to 20, in this embodiment, a plurality ofstandard cells include first and second standard cells which arearranged adjacent to one another in a direction (Y direction) orthogonalto a direction (X direction) in which impurity regions An and Ap forpower potential extend. Contact layers PCL are formed astride the firstand second standard cells.

Stated more specifically, for example, the n type active region An(impurity region for functional elements) of a standard cell Civ (firststandard cell) shown in the upper left of FIGS. 17 to 19 and the n typeactive region An of a standard cell Civ (second standard cell) shown inthe lower left of FIGS. 17 to 19 which are arranged on both sides of theimpurity region Ap for power potential as a power terminal VSS arecoupled to each other by the contact layer PCL (contact conductivelayer) having a contact portion SCT in the Y direction. That is, the ntype active region An and the impurity region Ap for power potential ofthe first standard cell Civ and the n type active region An of thesecond standard cell Civ are coupled to one another by the contact layerPCL.

The n type active region An and the impurity region Ap for powerpotential of the first standard cell Civ and the n type active region Anand the impurity region Ap for power potential of the second standardcell Civ which are coupled to each other by one contact layer PCL arejoined together at the junction portion BD. The above three regions An,Ap and An are in contact with the contact portion SCT of the abovecontact layer PCL. The power wire M1 to which VSS is applied is joinedto the contact layer PCL at the uppermost part of the above contactlayer PCL.

Owing to this configuration, the impurity region Ap for power potentialwhich extends below the power wire M1 as the power terminal VSS and then type active regions An on both sides (in the Y direction) of theimpurity region Ap are coupled to one another by one contact layer PCL.Therefore, the above three regions An, Ap and An are electricallycoupled to one another by a more simple wiring structure.

With reference to FIG. 21, FIG. 21 differs from FIG. 20 in that thepower wire M1 to which VSS is applied does not diverge in a directionorthogonal to a direction extending over the impurity region Ap forpower potential.

Also in this case, when the power wire M1 is coupled to the contactlayer PCL (at the same position as the impurity region Ap for powerpotential in the plan view) over the impurity region Ap for powerpotential, the impurity region Ap for power potential and the n typeactive regions An are coupled to each other by the contact layer PCL(contact portion SCT). Therefore, the above three regions An, Ap and Anare electrically coupled to one another.

Although not shown, when the contact layer PCL is made conductive to thepower wire M1 as in FIG. 16 even in this embodiment, if the contactlayer PCL (contact portion SCT) is arranged at a position where it doesnot couple the above three regions An, Ap and An to one another, it canelectrically couple the above three regions An Ap and An in anotherarea.

Since the configuration of this embodiment is almost the same as theconfiguration of First Embodiment except for the above points, the sameelements as in First Embodiment shown in FIGS. 17 to 21 are given thesame reference symbols, and their descriptions are not repeated.

Fourth Embodiment of the present invention differs from First Embodimentof the present invention only in the above points. That is,configurations, conditions, procedures and effect which are notdescribed for Fourth Embodiment of the present invention are all thesame as in First Embodiment of the present invention.

Fifth Embodiment

This embodiment differs from First Embodiment in the configurations ofthe impurity regions for power potential and the gate wires GW. Adescription is subsequently given of this embodiment.

FIG. 22 is a similar perspective view to the perspective view of FIG. 11of the standard cell of this embodiment. FIG. 23 is a plan view of FIG.22. Further, FIG. 24 is a plan view of a relatively lower layer(excluding the power wire M1 in FIG. 23) of the standard cell shown inFIG. 22 and FIG. 23 like FIG. 4.

With reference to FIGS. 22 to 24, in the standard cell of thisembodiment, a pair of p type source/drain regions Ap of a MIS transistorare formed over the main surface of the n type well region An of thesemiconductor substrate SB (see FIG. 7) with a space therebetween. Thegate wires GW (gate electrodes) of the above MIS transistor extending inthe longitudinal direction of FIG. 23 and FIG. 24 are formed in such amanner that they extend over an area between the pair of p typesource/drain regions Ap.

An n type impurity region An for power potential which is joined to thep type source/drain regions Ap at the junction portion BD is arrangednext to the p type source/drain regions Ap. The width in the X directionin the plan view of the n type impurity region An for power potentialand the width in the X direction in the plan view of the p typesource/drain regions Ap near the junction portion BD are substantiallythe same. Above the impurity region An for power potential, especiallyabove the gate wires GW is arranged a power wire (first metal wire) M1.This power wire M1 is for supplying VDD or VSS potential.

The impurity region An for power potential and the power wire M1 are notelongated in the X direction and are divided into two.

One (first power wire) of the two power wires M1 extending in the Xdirection and the other (second power wire) are electrically coupled toeach other by contact layers PCL through a conductive layer GW forcoupling extending in the X direction like the power wires M1. The twopower wires M1 and the conductive layer GW for coupling overlap witheach other in the plan view in the contact layers PCL. The conductivelayer GW for coupling extending in the X direction is made of the samematerial as the above-described gate wires GW extending in the Ydirection. The conductive layer GW for coupling extending in the Xdirection and the gate wires GW extending in the Y direction areseparated from each other from the same layer.

One of the two impurity regions An for power potential is electricallycoupled to the first power wire M1 and the other impurity region An iselectrically coupled to the second power wire M1 by the contact layersPCL.

The first and second power wires M1 and the impurity regions An forpower potential are electrically coupled to each other by the contactlayers PCL having a contact portion CT. However, the first and secondpower wires M1 and the impurity regions An for power potential may beelectrically coupled to each other by the contact layer PCL having thecontact portion SCT as shown in First Embodiment.

Further, in this embodiment, a wire layer M1 separated from the samelayer as the power wires M1 is formed between the separate power wiresM1. This wire layer M1 extends in the Y direction and is situatedbetween the first and second power wires M1 extending in the Xdirection.

The p type source/drain regions Ap and the n type impurity regions Anfor power potential are preferably made of Si, for example. However,when the p type source/drain regions Ap are made of SiGe in place of Si,with reference to FIG. 25, the chances of the occurrence ofdisconnection at the junction portion BD between the p type source/drainregions SAp made of SiGe and the linear n type impurity region An forpower potential made of Si become high. This is because it is difficultto form a low-resistance silicide layer for smoothing conduction betweenthe contact portion CT or SCT and the contact layer PCL over the mainsurfaces of the p type source/drain regions SAp and the n type impurityregion An for power potential when they are made of different materials.

When the p type source/drain regions SAp are made of SiGe, the currentdrive capability of the p type source/drain regions SAp improves.However, when disconnection occurs at the junction portion BD, the ptype source/drain regions SAp change their shapes in the plan view andthe function of the p type source/drain regions SAp may deteriorate.

Then, to make the active regions and the impurity region for powerpotential from the same material, for example, when the impurity regionSAn for power potential is composed of a SiGe layer in addition to the ptype source/drain regions SAp as shown in FIG. 26, disconnection mayoccur in the linear (elongated) impurity region SAn for power potentialmade of SiGe.

However, in this embodiment, the n type impurity region for powerpotential is divided in the X direction and not linear (elongated).Therefore, both the n type impurity region for power potential and the ptype active region may be made of SiGe. When both of them are made ofSiGe, standard cells having improved current drive capability andsuppressed disconnection can be provided. In this case, the conductivelayer GW for coupling extending in the X direction is preferably a metalgate containing titanium or copper. In this case, the gate wires GWbecome similar metal gates.

Since the configuration of this embodiment is almost the same as theconfiguration of First Embodiment except for the above points, the sameelements as in First Embodiment in FIGS. 22 to 28 are given the samereference symbols, and their descriptions are not repeated.

A description is subsequently given of the function and effect of thesemiconductor device SDV of this embodiment with reference to FIGS. 23to 24 and FIGS. 27 and 28.

As shown in FIG. 27 showing a comparative example to this embodiment andFIG. 28 in which the power wire M1 in FIG. 27 is not shown, an STIregion RE surrounded by the p type source/drain regions Ap assource/drain regions and the n type impurity region An for powerpotential in three directions in the plan view is formed. Although aninsulating layer is buried in the STI region RE, as long as the STIregion RE is surrounded by An and Ap in the three directions, it isdifficult to bury insulating layers II1 and II2 in the STI region RE.

Therefore, like this embodiment, the impurity region An for powerpotential is not elongated in the X direction but divided. Thereby, theSTI region RE in FIG. 23 and FIG. 24 is surrounded by the p typesource/drain regions Ap in two directions. Since the STI region RE isnot surrounded by An and Ap in the other two directions, as comparedwith the configuration shown in FIG. 27 and FIG. 28, it is easy to burythe insulating layer II1 in the STI region RE.

Since it is easy to bury the insulating layer II1 in the STI region RE,variations in the shapes in the plan view of the surrounding p typesource/drain regions Ap and the n type impurity region An for powerpotential can be suppressed. That is, the performances of the formed MIStransistors and the standard cells are stabilized.

Since the impurity region An for power potential is not elongated in theX direction, the power wire M1 formed over the impurity region An forpower potential does not need to be elongated in the X direction. Thatis, the degrees of freedom of the length in the X direction and thelocation for dividing the power wire M1 increase.

Further, as the power wire M1 is divided into two (first and secondpower wires), a power wire M1 extending in the Y direction can bearranged in the divided area. When FIG. 23 and FIG. 27 are compared witheach other, the position of the power wire M1 extending in the Ydirection is different. As described above, the degree of layout freedomof the power wire M1 formed by one-dimensional layout having no bendingand curving increases.

When the impurity region An for power potential is elongated as shown inFIG. 27 and FIG. 28 as described above, a trouble may occur by usingSiGe in the impurity region An for power potential. However, since theimpurity region An for power potential is divided short like thisembodiment, SiGe can be used in the impurity region An for powerpotential. If the p type active region Ap is made of SiGe, the currentdrive function improves and a high-performance standard cell in whichdisconnection at the junction portion BD is suppressed can be provided.

The configuration of an area including the impurity region An for powerpotential and the p type active region Ap arranged below the power wireM1 for supplying the potential of the power terminal VDD has beendescribed above. However, in the area including the impurity region Apfor power potential and the n type active region An arranged below thepower wire M1 for supplying the potential of the power terminal VSS (seeFIG. 4), the same structure as above may be formed.

The semiconductor device of the present invention may be configured bysuitably combining the above embodiments. In this case, the effectsdescribed for the combined embodiments can be provided likewise. Itshould be understood that the embodiments disclosed herein areillustrative and not restrictive. Since the scope of the presentinvention is defined by the appended claims rather than by thedescription preceding them, and all changes that fall within meets andbounds of the claims, or equivalence of such meets and bounds aretherefore intended to be embraced by the claims.

The present invention can be especially advantageously applied to asemiconductor device having standard cells.

1. A semiconductor device having a plurality of standard cells,comprising: a semiconductor substrate having a main surface; a firstconductive impurity region for functional elements which is formed overthe main surface of the semiconductor substrate in at least one of thestandard cells and forms functional elements; a second conductiveimpurity region for power potential which is formed over the mainsurface of the semiconductor substrate in the at least one of thestandard cells and to which a power potential is applied; an insulatinglayer which is formed over the main surface of the semiconductorsubstrate and has throughholes reaching the main surface of thesemiconductor substrate; and a conductive layer for contact which isformed in the throughholes of the insulating layer, wherein theconductive layer for contact is formed astride the impurity region forfunctional elements and the impurity region for power potential so as toelectrically couple the impurity region for functional elements and theimpurity region for power potential therethrough.
 2. The semiconductordevice according to claim 1, wherein the impurity region for functionalelements and the impurity region for power potential are coupled to eachother right below a contact region where the conductive layer forcontact is in contact with the main surface of the semiconductorsubstrate.
 3. The semiconductor device according to claim 1, wherein theimpurity region for functional elements and the impurity region forpower potential are not joined together and separate from each otherright below the contact region where the conductive layer for contact isin contact with the main surface of the semiconductor substrate in theplan view.
 4. The semiconductor device according to claim 1 furthercomprising a power wire extending over the impurity region for powerpotential, wherein the power wire is joined to the conductive layer forcontact.
 5. The semiconductor device according to claim 1, furthercomprising a power wire extending over the impurity region for powerpotential, wherein the power wire is not joined to the conductive layerfor contact and is separate from the conductive layer for contact. 6.The semiconductor device according to claim 1, wherein the standardcells include first and second standard cells which are arrangedadjacent to each other in a direction orthogonal to a direction wherethe impurity region for power potential extends, and wherein a contactregion where the conductive layer for contact is in contact with themain surface of the semiconductor substrate is arranged astride thefirst and second standard cells.
 7. The semiconductor device accordingto claim 1, wherein the impurity region for functional elements is madeof either one of SiGe and SiC and the impurity region for powerpotential is made of Si.
 8. The semiconductor device according to claim2, wherein the contact region is situated within an area where theimpurity region for power potential and the impurity region forfunctional elements are formed without being projected from the areaover the main surface of the semiconductor substrate in a plan view.